Drug discovery can include biological testing of candidate compounds by exposing the candidate compounds to samples of tissue that exhibit the disorder to be treated. For example, in screening candidate compounds for efficacy against atherosclerosis, endothelial cells can be exposed to a shear stress, which affects the growth and behavior of adherent cultured cells. In some implementations, the cultured cells react more like in vivo cells when a shear stress (also referred to as shear force) that mimics in vivo conditions is applied to the cultured cells.